To meet the growing demands of the personal computer (PC) consumer, personal computer manufacturers are constantly improving system performance in microprocessor speed and functionality, memory speed and size, power consumption, visual quality, and input/output performance. Manufacturers improve personal computers through technological advances in the processes used to fabricate the integrated circuit devices within the personal computer and/or through hardware or software design improvements. The personal computer manufacturers often strive to implement these technological or design advances into consumer available products as soon as possible in order to keep up with consumer demand and to compete with other computer manufacturers.
With the rapid advances in technology, a computer system can become obsolete in relatively short amount of time so consumers often desire to upgrade their current systems to obtain the processing advantages of more advanced systems in the most cost effective manner.
One way in which a consumer may upgrade their computer system is by replacing the motherboard. The motherboard of a computer system contains and interconnects the main microprocessor, a clock generation device, and other integrated devices and components that determine the functionality of the system. However, replacing the old motherboard as a unit tends to be a narrow upgrade path for the consumer since it is limited by the physical constraints of the computer housing in which the motherboard resides. As the size of personal computers are reduced, future motherboards have different shapes and sizes. Also, replacing the motherboard is relatively expensive and requires a certain degree of skill, so oftentimes is not a viable option to the consumer.
In addition, from the perspective of a computer manufacturer, redesigning motherboards is a time consuming process. It takes close to a year to design and test a new motherboard. During this time, new non-motherboard upgrades cannot be made available to the consumer and neither manufacturers nor consumers gain the benefits of the technological advances to microprocessors until the redesigned motherboard is ready.
The better ways of upgrading involve replacing the current microprocessor residing on the motherboard with a new, upgraded microprocessor. Redesigning a microprocessor is more cost and time effective than redesigning a complete motherboard. In general, the upgraded microprocessors are designed to be faster and more power efficient than their predecessors due to newly developed technologies and circuit designs.
Faster microprocessors require a faster clock. Since clocks are generally on the motherboard, replacement of the microprocessor requires modification of the clock signals from the motherboard. Generally, the original clock signal from the motherboard must be multiplied up to the faster rate required by the new microprocessor. The circuitry for increasing the rate of the motherboard clock is provided for in the microprocessor, but unfortunately, it can be tuned to increase the clock rate only for a given motherboard clock rate.
Another disadvantage of only replacing the microprocessor is that the new microprocessor is designed to upgrade only a particular motherboard design. This is because the microprocessor I/O bus is designed to have a communication protocol that is adaptable to only a particular motherboard design.
Another problem with replacing the microprocessor occurs where the personal computer manufacturers offer a family of computer systems with each system having different features. In order to provide these different features, each family member has a corresponding different motherboard design adapted to a particular microprocessor. Due to the different motherboard design, a microprocessor produced to upgrade one family member cannot be employed for upgrading another family member. For example, it might not be possible to upgrade the lower-end microprocessor in a family member with a higher-end microprocessor from the same family.
One solution to the clock problem on the motherboard is to fix the maximum motherboard clock speed and provide jumpers on the motherboard so the microprocessor clock speed can be changed manually when the microprocessor speed is known. Unfortunately, this requires a high degree of skill on the part of the consumer which leads to their often buying another computer rather than risk damage to the computer by working in its entrails.
Another solution to this problem is to develop a microprocessor daughter card that contains the microprocessor and a clock, and to remove the clock from the motherboard. The clock would be set up to provide clock signals appropriate to the motherboard and also be subject to the multiplier circuitry in the microprocessor to provide clock signals appropriate to the microprocessor. This is much easier on the consumer who wishes to upgrade.
The two drawbacks to this last solution are that the maximum speed capability of the motherboard must be known (and acts as a limit to upgrading motherboards) and that the multiplier circuitry must be preselected for each microprocessor daughter card depending on the maximum speed capability of the motherboard.
A system has been long sought which would allow upgrades merely by insertion of a new, faster microprocessor without prior knowledge of the motherboard in which the faster microprocessor would be inserted. This system has long eluded those skilled in the art.
Also, a system has long been sought which would allow an original equipment manufacturer (OEM) to design a motherboard in anticipation of a better microprocessor which is expected but is not yet available. The OEM would like to use up the inventory of existing microprocessors using the new motherboard and be able to switch over to the new microprocessor immediately when it becomes available.